HD movie selection is limited: Of the top 50 iTunes movie purchases, we could only find 5 that were available for purchase (or pre-order) in HD.

Rentals will cost $4.99 and HD downloads will cost $19.99.

We don't expect this to make a significant impact on Apple's business, but it makes the new iMac a more attractive bedroom TV, and could make the new Mac mini a more attractive set-top box, which could help Apple sell a few more units.